Drill grinding machine



June 17, 1941.

E. J. HORNBERGER DRILL GRINDING MACHINE Filed Jan. 26, 1940 5 Shee's-Sxeerl 1 INVENTOR- Earl Ji'bnbe @WITNES l W w A TTORNE YS.

June 17, 1941; E. J. HORNBERGER DILL GRINDING MACHINE '5 sheets-sheet 2 Filed Jan. 26, 1940 INVENTOR Z J frn/be2 ATTORNEYS.

, www1 June 17, 1941. E J, HORNBERGER 2,245,858

DRILL GRINDING MACHINE Filed Jan. 26, 1940 5 Sheets-Sheet 5 W1 TNESSES:

l N VEN TOR:

A TTORNE YS.

Earl Jirnberyer .June 17, 1941. E. J. HORNBERGER 2,245,858

DRILL GRINDING MACHINE ,Filed Jan. 26, 1940 5 Sheets-Sheet 4 FIG; 1Q;

WITNESSES; INVENTOR;

Earl 7. brizberqe 2;.

@W3-YW ATTORNEYS June 17, 1941. v

E. J. HORNBERGER DRILL GRINDING MACHINE Filed Jan. 26. 1940 APPROX. FEL/EF' T-A- 5 Sheets-Sheerl 5 APPROX- FEL/EF ATB INVENTOR.- Earl Jrnberyer www 7 ATTORNEYS.

Patented June 17, 1941 UNITED STATES PATENT OFFICE Dam. Gamme MACHINE Earl J. Hornberger, Philadelphia, Pa. application January 26, 1940, Serial No. 315,711

15 Claims.

This invention relates to .grinding means for sharpening the points'or cutting edgesof twist drills and the like, and it has for a general object to provide a machine enabling such procedure to be effected with greater accuracy than heretofore, and preassurance that both cutting edges are of exactly corresponding size with the point of mergence directly through the axial center of the drill.

Another object of this invention is to provide a grinding machine including means whereby the relief angle of the drill is greater at or near the center than at the outer edges of said drill.-

Y/Y-Further/ollects'have' reference to improved means whereby ldrills having various cuttingangles can be readily ground; an improved machine of the indicated type capable of accurately pointing twist drills; a machine equipped for readily re-dressing the active face of the grinder member without removal from said machine and accurately resetting the latter after such operation to the proper point of intersection; a machine including graduated dials whereby the operator, without consulting charts or resorting to guesswork, can set said dials in accordance with the size of drill to be ground so that the desired point will be correctly produced. l In addition to the foregoing objects, it is an aim of the instant .invention to furnish a grinding machine that is convenient and simple in structure, as well as very efcient in operation.

Still further, objects and ancillary advantages of this invention .will hereinafter appear, as the nature thereof is'- more fully explained, said invention consisting substantially in certain novel features of construction, the combination and correlation of parts hereinafter disclosed, and illustrated by the accompanying drawings of a typical embodiment, wherein corresponding reference characters are used to designate similar parts throughout the several views; while the concluding claims more particularly recite the features of novelty.

In the drawings: Fig. 1 is a plan view of a drill grinding machine Fig. 10 a fragmentary end view looking toward the A'ctive endl of the grinder head, but drawn to much larger scale for purposes of clarity.

Fig. 11 is a perspective view of a collet-closure sleeve hereinafter fully described. l

Fig. 12 is a similar type view of the collet.

Fig. 13 is a. fragmentary view of the nose portionl of a twist drill having the point ground by the improved machine of this invention.

Fig. 14-is a similar view, but taken at 'rightangles to the preceding lgure. Y

Figure 15 is a schematic view hereinafter fully explained.

Figs. 16-20, inclusive, are diagrammatic views illustrating h ow the novel angle of relief is ob' tained with the grinding machine of this invention.

In the following detailed description of the embodiment of this invention illustrated in the accompanying sheets of drawings,I speclc terms purpose.

Referring more in detail to the drawings which illustrate a typical embodiment of the invention,

`preferably adapted for the grinding or re-sharppart. f A

Mounted in bearings 6, 'I, in the base I, with capacity for limited axial movement, is a bar or embodying one practical'form of this invention.

Fig. 2 is apart elevation and part sectionof the same.

Fig. 3 is an end view looking from the right towards the left-hand of Fig. 2.

Fig. 4 is an axial section through the chuck-- head and associated parta-.taken on the plane IV-IV in Fig. 2.

Fig. 5 is a detail section on the plane V-V in Fig. 2.

shaft l restrained against rotation by a drop pin 9, in the bearing'6, havlng a diametric tooth Il engageable in a longitudinal groove II with inclined ends, for puIDOses of elevating the pin 9 when it is desired to remove the shaft 8 from the base I.- The one end of the shaft 8 is screwthreaded at I2 and fitted with an adjuster or feed nut I3 for imparting axial movement to said shaft outwardly relative to the drop pin 9, for a purpose later on more fully explained;' while Il designates a conventional pull-and-push type switch controlling supply of electric current to the motor 2.

The shaft 8 projects outwardly beyond the bearing 1 to furnish a swingable-bearing I5 for an elbow support comprehensively designated I6, said bearing comprising a pivotal-portion l1, tting the shaft 8, and an angularly-related branch I8 with spaced projections I8', Fig. 3. 'I'he elbow support I at its inner end is provided with a relatively reduced part I9 having a longitudinal rib 20, normally engaging a correspondingly sectioned groove 2 I, in the bore 22 of a cup-piece 23 abutting the base bearing 1, said cup-piece being provided with an arcual slot 24 into which a stationary pin 25,' projecting outwardly from the bearing 1 engages; whereby provision is aorded for conjoint and limited movement of the bearing I5 and the cup-piece 23, as later on further amplied. Seating in a bore 26, o f the body portion reduced end I9, is a spring 21 in abutment against the inner end of the cup-piece 23,'whereby the swingable-bearing I5 is normally forced outwards against a stop-collar 28 fitted with a drop-pin 29 embodying a diametric tooth 30, engaging in a movement limiting groove 3I, longitudinally of the screw-threaded end 32 of the shaft 8. 'I'his screw-threaded end 32 is of a much coarser pitch than the remote end I2, of

the shaft 8, and it is .fitted with an adjuster-nut,

33 having graduations 34, Fig. 3, varlably registerable with a zero-mark Z on the stopcollar 28.

Firmly screwed at 35 into the swingable-support angular branch I8 is an axis member 36, fitted with an eccentric bushing 31 and embodying a circumferential flange 38 having graduations 38', said flange abutting the confronting face of the angular branch I8. The bushing 31 is restrained against axial movement by a washer 39 and screw 40, threadedly engaged in the correspondingly-bored outer end of said axis member.

Mounted on the bushing 31 is the elbow support I6, hereinbefore referred to, said support having one part' provided with a movement limiting lug I6' for coaction with the spaced projections I8' aforesaid, and it is bored at 4I for frictional engagement over the bushing 31, so that it is normally rotative therewith, but may be relatively moved, for a purpose later on set forth. 'I'he other part of the elbow support I6 is formed with a head or eye-bearing 42, the axis whereof is preferably directed at an angle of 59 from the vertical for production of the conventional drill pointangle.

Mounted in the eye-bearing 42 with capacity for axial adjustment is the work-head which comprises a sleeve 43, having a flange 44 apertured at 45 for passage of a feed-screw 46, threadedly engaging a corresponding bore 41. in the elbow support I6, said bore being parallel with the axis of the sleeve 43; while the screw 46 is provided with a collar 48, and a knurled manipulator-head 48, for jointly effecting movement of the work-head, hereinafter comprehensively referred4 to as 5l. Clamped in the sleeve 43 by aid of a ange 5| and a screw-threaded lock-collar 52 is a sleeve chuck 53, said chuck being restrained against rotation relative to the sleeve 43 by a locking screw 54, Figs. 2 and 'Land having the end facing `the grindinig wheel 4 tapered at 55,for abutting coaction with the correspondingly-shaped end 56' of a collet-closer 56; said vcloser in turn receivingv the shouldered collet 51. The closer 56 is caused to tightly grip the collet 51, by means of a screwcap 58 engaging its outer threaded-end 59 in opposition to the tapering coaction set up between the taper parts 55 and 56'.

In order to properly align'and set the collet 51 in the closer 56, with respect to the cutting edges of a drill to be ground, the former 51 is provided with a longitudinal rib60 at right angles to the conventional diametrically opposed slots 6I, while the latter 56 is formed with a similar and correspondingly disposed rib 62, beyond the outer ends of its slots 63, see Figs. 11 and 12. The respective ribs 60, 62 engage like sectioned and aligned grooves 64, 65, respectively. in the bore of the collet closer 56 and sleeve chuck 53, as best understood from Fig. 4. Thus it will be seen that a 'simple means is provided for accurately aligning the cutting edges of the drill in registration and parallelism with the diametrically opposing slots 6I and 63 of the collet 51, and its closer 53, respectively, as readily understood on an examination of Fig. 10.

An index latch 66 is fulcrumed at 61, in a gap 68 provided for the purpose in the work-head flange 44, with a fork-portion 69 thereof abutting the enlargement 10, intermediate the ends of a plunger 1I, movable in a. bore 12 in the eye-bearing 42 in opposition to a spring 13. 'Ihe outer portion lof the plunger 1I is engageable with either one of diametrically-opposed holes 14 in the lock-collar 52, so that the work-head 50 can be rotated through and effectively held for grinding the point angles or lips 15 of the drill 16; see l-igs.---10.-l3 and 14 to best advantage. 18, Fig, 1, designates'nindex setting the point of intersection 19, Fig. l5, of the axial lines through the work-head 5D and that passing up through the axis member 36 relative to the face 5 of the grinder 4.

Having explained the structure of the invention the operation is briefly as follows. 'Ihe drill 16 to be ground is first inserted in the collet 51 until the point thereof projects outward of said collet, a distance. approximately equal to the diameter of said drill, whereupon the latter is turned until the cutting edges or lips 15 align with the collet slot, as clearly shown in Fig. 10, when the spring tension inherent inthe collet 51 holds said drill in place. 'Ihe collet 51, with the inserted drill, is now placed in the closer 56, and the latter tightened-up by the'screw-cap 58, in an obvious manner. The dial flange 38 is next turned to the graduation reading 38' corresponding to the size of the drill 16 to be ground, when the adjuster nut 33 is similarly turned with respect to the graduations 34, whereupon the motor 2 is started by the switch I4. The feed-screw 46 is now turned by its head 49 to advance the point of the drill 16 into contact with the face 5 of the grinder 4; whereupon the operator manually swings the work-head 50 on the axismember 36 in accordance with known practice. After the first lip 15 of the drill 16 has been ground, the entire work-head 50 and elbow I6 are bodily tion within the limits of the projections I8', as

gage .cr initially defined by the lug I6. The work-head index latch 66 is now moved clockwise to release the lock device 18, whereupon the chuck 53 is given a half-tum and said device 10 allowedto snapback into active position under the influence of `the spring 13, which resultsv in placing Vthe other as aforesaid, whereby the drill lis emciently ground ready for removal from the collet 51 by a reversal of the inserting operation above rst explained. By holding the drill 16 in the manner point, for grinding. or re-setting' purposes, any slight deilection inthe body of said drill will not cause the point to be ground o-center.

Another feature of advantage of this invention is that the relief `"angle 80 isslightly greater at or near the center than at the outer edges, which is highly desirable in order to prevent rubbing near the center when the relief angle 80 at the outside edges is correct for obtaining the most desirable boring action. The importance of this dinerential relief angle 80 will be readily nderstood from an inspection of Figs. 15-'2 inclusive, and wherein explanatory legends are shown for purposes'of comparison. The letter-D designates the center line of a drill 16 in 'approximately .its proper lrelation to the vface of the grinder 4; E is the-axis on which thev drill 16 is rotated while being ground, the center line of said drill being set some distance back of axis E. The relief radius produced at point A near the outer edge of the drill 16 is indicated-in Figs. 17

' and 18 as approximately ive degrees at the .cut-

tingedge; while the relief radius at the point B near the center than at the outer edges of the drill16. With the grinder of this invention, the relief angle 80 on the end of\.a drill 16 can readily be varied to) suit said drill to the rate of penetration best adapted for the material being drilled. This variation is accomplished by simply setting one or both of the graduations 34, 38', on the adjuster nut 33 and bushing flange 38 to a point above or below the standard graduation's.A The radius of the relief angle to be 'ground on the pointeof a drill is determined by thegraduations 34 on the adjuster-nut 33, said graduations being defined to read directly proportional to the diameter of the. drill 16 being ground. The centerA line of the drill 16 being ground ,is not in the same plane as the axis on which the elbow-support I6 oscillates whilegrinding the drill 16; while the amount the centerv line aforesaid is offset by the bushing 31, see Fig. 9, is determined by the size of the drill 16 being ground and is set 'at approximately one-sixth of the diameter of said drill, by rotation of the eccentric bushing? flange 33, thegraduations whereon are d'ened to -read directly on theproper adjustment lcorresponding to the size of drill toy be ground. Furthermore, adjustment .of thenut 33 causes the inner face of the-eye-bearing 42, by rotation oi' the feed-screw 46 to move the work-head 50, relative to the elbow-bearing I6, and then screwing-up on the nut 33, with the graduations 34 and 38 both at zero, the proper point of intersection 19 is obtained; or the same adjustment is per-4 formed when -the grinder machine has been used and the operator desires to reassure himself the correct point of intersection obtains before in` sertinga fresh drill to, be ground. It is also to be noted that by axially moving the work-head 50 and rotating the eccentric sleeve 31, various angular points can be given thedrills. Finally, it

' willbe seen that the drill vpoint is ground on. a

variable eccentric curvature relative to thev axis of the drill, in conformity with piercing and primal cutting requirements, so that the initial borings are laterally displaced before entry into the drill cutting spiral.

'I'he machine illustrated is well adaptedA for handling drills from three-sixteenths of an inch diameter down to and including drills of .020

-inch diameter. However, it will be apparent that by obvious changes the machine is equally` well adapted for grinding drills of larger sizes without departing from the spirit and scope of the invention. y

Having thus described my invention, I claim: l. In a machine of the type described including a rotary grinder with a stationary base, the combination of a drill-holder including a` sleeve with means for adjusting it along an inclined near the center of said drill, swinging on radius D axis; an elbowsupport for the drill-holder sleeve, said support having a fulcrum bore with an eccentric-section bushing therein; movable bearer .means associated with the stationary base` having an axis-member engaged in the bushing bore; means for rotating the bushing to determine the relief angle given'the drill point; and means for adjusting the movable bearer relative to the stationary base for setting the point of intersection of the elbow-support axis of oscillation with that. of the drill holder in respect to the active face of the rotary grinder.

2. In a machine ofthe type described including a rotary grinder with a stationary base, the

` combination of a drill-holder including a sleeve with means for adjusting it along an inclined axis; means whereby the drill-holder may be given a half-turn relative to its associated sleevev and elfectively held at the limits of such halfturn while grinding the drill point lips; an elbowsupport for the drill-holder sleeve, said support having a fulcrum bore with. an eccentric-section bushing therein; movable bearer means associated with the stationary base having 'an axis.

, member engaged in the bushing bore; means for the entirework-head 50 and its`support I 6 to be 'rotating the bushing to'determine the relief angle,

given the drill point; and means for adjusting the. movable bearer relative to the stationary base for setting the point of intersection of the elbow-support axis of oscillation with that of the drill holder in respect t the active face of the rotary grinder. l

3.- In a Amachine of the type described including.a rotary grinder with a stationary base, the combination of a drill-holder including a sleeve with means for adjusting it along an inclined` axis; means whereby the drillholder may 'be given a half-turn relative to its associated sleeve and elfectively held' atl th'e limits` of such halfturn whilegrinding the drill point lips; an elbow.- y support for the drill-holder sleeve, said support having a fulcrum borewith an eccentric-section bushing therein; movable bearer means asso` ciated with the stationary base having an axis member engaged in the bushing bore; means limiting arcual rotation of the bearer means out-l wards and inwards from a predetermined grinding position for insertion of a drill into, and its removal from, the holder; means for rotating the bushing to determine the relief angle'given the drill point; and means for adjusting the movable bearer relative to the ystationary base for setting the point of intersection of the elbow-support axis of oscillation with that of the drill holder in respect tothe active face of the rotary grinder.

4. In a machine of the type described including a rotarygrinder with a stationary base, the combination of a drill-holder including a sleeve with means for adjusting it along an inclined axis; an elbow-support for the drill-holder sleeve, said support having a fulcrum bore with an eccentric-section bushing therein; movable bearer means associated with the stationary base having an axis'member engaged in the bushing bore; means for rotating the bushing to determine the relief angle given the drill point; and an axially shiftable bar sustained by the stationary base with adjuster devices for setting the point of intersection of the elbow-support axis of oscillation with that of the drill-holder in respect to the active face of the rotary grinder.

5. In a drill-grinding machine, a base with a surmounted motor; a grinding wheel on the shaft of the motor; a bar extending through bearings in the base with means restraining it against rotation; means permitting controlled axial adjustment of said bar; a pivotal bearer on one end of the bar embodying an angularly-related branch with spaced projections and an axis member; means in the form of a pin-and-slot connection limiting pivotal movement of the bearer relative to the bar; an eccentric bushing on the axis member, said bushing having a circumferentially graduated flange; an elbow-device having one portion bored for frictional engagement over the eccentric bushing, and the other part embodying an eye-bearing, the axis whereof is directed at a predetermined inclination from the vertical; a work-head sleeve extending through the eye bearing; a chuck in said sleeve with means restraining said parts against relative rotation; a collet closer and collet in the chuck for reception of a drill to be ground; latch means controlling rotation of the chuck; a lateral lug on the elbow-device engageable with the pivotal bearerA spaced projection for limiting oscillatory movement of said elbow-device; and adjuster means coactive with the work-head sleeve and elbow-devicefor axially moving said sleeve and the collet as a unit towards or away from the active face of the grinding wheel.

6. A drill grinding machine as dened in claim 5, wherein the base bar is disposed in par- Y allel below the motor shaft, and the means re straining it against rotation comprising a longitudlnal groove therein and a drop-pin through Van adjoining bearing wall having a tooth enf gageable in said groove.

7. A drill grinding machine as defined in claim 5, wherein the means permitting adjustment of the base bar comprise screw-threaded end portions thereof; a graduated adjuster nut with or securing nut on' the other screw-threaded end of the base bar aforesaid.

8. A drill grinding machine as defined in claim 5, whereiny the pivotal bearer on the base sustained bar has one'end reduced and bored; a cupdevice coacts withthe pivotal bearer reduced end, said `reduced end having a longitudinal rib for coaction with aAcorrsponding groove in the cupdevice to prevent relative rotation; a spring in compression housed within the cup-device and -pivotal bearer bored end forces said bearer against a stop collar on the base bar; and a pin projects from the machine base into an arcual slot in the cup-device for limiting conjoint rotary movement of the pivotal bearer and cup-device relative to the base bar.

9. A drill grinding machine as dened in claim 5, wherein the elbow-device and eccentric bushing have a friction flt to ensure normal joint rotative movement, and said bushing is restrained against axial movement by a washer and screw threadedly engaging the pivotal bearer branch axis-member.

10. A drill grinding machine as defined in claim 5, wherein the work-head sleeve is provided with a flange having an aperture therethrough, and a feed-screw rotatively engages through said aperture with its threaded portion operatively engaging in a corresponding screwbore paralleling the axis of the work-head sleeve.

11. A drill grinding machine as defined in claim 5, wherein the chuck is in the form of a sleeve hav'ing the end portion facing the grinding wheel tapered, said chuck sleeve being provided with a flange for abutment against one end of the work-head sleeve, a screw-threaded lock-collar on the other end of the chuck sleeve for clamping it to the work-head sleeve, and a radial screw through the lock collar secures the latter to .the chuck sleeve.

12. A drill grinding machine as defined in claim 5, wherein the chuck is in the form of a sleeve fitted with a clamping collar having a pair of diametrically-spaced holes therethrough, a spring-influenced plunger having an enlargement intermediate the ends is housed in a bore in the elbow-device eye-bearing, said plunger outer end being engageable in either of the collar holes aforesaid, and an index latch ful crumed in a gap in a flange on the work-head sleeve, said latch having a fork portion abutting the plunger enlargement outer face, for effecting release of the plunger from the clamping collar holes to permit half-rotation of the chuck sleeve.

13. A drill grinding machine as defined in claim 5, wherein the chuck is provided with a tapering active end portion, the collet-closer is diametrically split longitudinally for a predetermined distance correspondingly tapered and provided with a longitudinal rib beyond the split portion for engagement in a complemental groove in the work-head sleeve, the collet is similarly split and provided with a longitudinal rib midway therebetween, said rib being engageable in a groove interiorly of the collet closer, and a `screw-capl on the end of the chuck remote from its tapering end operative to clamp the colletcloser and collet'rmly about a drill in opposition to the chuck active end.

1 4. A drill grinding machine as defined in claim 5, wherein the chuck is provided with a tapering active end portion, the collet-closer is diametrically split longitudinally for a prede- -termlned distance and correspondingly tapered metete 15. In a drill grinding machine as dened in claim 5, wherein the collet closer active portions are adapted when clamped on the collet to eieet substantial grippage lengthwise of the drill web inwardly of the drill point, .whereby said point when ground is positively generated concentric with said web and with two cutting edges of identical size.

EARL J. HORNBERGER. 

